Multi-layered films oriented in the machine direction and articles comprising the same

a multi-layered film and machine direction technology, applied in the field of uniaxial orientation multi-layered films, can solve the problems of limiting the thickness of films without sacrificing toughness, tear strength, and/or stiffness required for conversion processes, bagging operations, and/or end use functional performance, and achieve desirable mechanical properties and tear strength. desirable

Active Publication Date: 2022-01-04
DOW GLOBAL TECH LLC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The film exhibits a limited drop in tear strength and maintains high mechanical properties even after orientation, providing a balance of stiffness and toughness suitable for flexible packaging applications.

Problems solved by technology

However, there are limits on how thin the films can be without sacrificing toughness, tear strength, and / or stiffness required for conversion processes, bagging operations, and / or end use functional performance.
However, when oriented significantly in the machine direction (e.g., at draw ratios of 6:1 to 10:1), such films can become weak in tear strength in the machine direction due to the unidirectional orientation.

Method used

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  • Multi-layered films oriented in the machine direction and articles comprising the same
  • Multi-layered films oriented in the machine direction and articles comprising the same
  • Multi-layered films oriented in the machine direction and articles comprising the same

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0105]

TABLE 2Thickness4.8:1 Draw6.2:1 DrawLayerComposition(μ)Ratio (μ)Ratio (μ)A (First70% EPE-HD;28.386.925.27Layer)30% Z-N ULDPEB (InnerEPE-HD56.7713.8410.54Layer)A (Second70% EPE-HD;28.386.925.27Layer)30% Z-N ULDPETotal Thickness113.5427.6921.08

Both films are substantially flat and are quite stiff with the 21 micron film having lower haze and higher gloss. Measurements are taken to evaluate the Example 1 films orientation performance. The 21 micron Example 1 film had an initial roll width of 1400 mm, a roll width after orientation in the machine direction of 1180 mm, and a final roll width after edge trimming of 1040 mm. These values represent a width retraction after orientation in the machine direction of 15.71%, and a total width reduction of 25.71% after additional trimming of slightly thicker film edges after orientation.

Example 2

[0106]Table 3 shows the film structure for Example 2. Example 2 also has an A / B / A film structure and includes the same EPE-HD and Z-N ULDPE as Exam...

example 2

[0111]

TABLE 46.2:18.3:19.1:1ThicknessDrawDrawDrawLayerComposition(μ)Ratio (μ)Ratio (μ)Ratio (μ)A (First70% EPE-HD;29.535.464.063.94Layer)30% Z-NULDPEB (InnerZ-N ULDPE59.0610.928.137.89Layer)A70% EPE-HD;29.535.464.063.94(Second30% Z-NLayer)ULDPETotal118.1121.8416.2615.77Thickness

Measurements are taken to evaluate the Example 2 films orientation performance. The 16.26 micron Example 2 film has an initial roll width of 1400 mm, a roll width after orientation in the machine direction of 1200 mm, and a final roll width after edge trimming of 1050 mm. These values represent a width retraction after orientation in the machine direction of 14.29%, and a total width reduction of 25.00% after additional film edge trimming to remove the slightly thicker edges.

[0112]The Example 2 films are measured for Elmendorf tear according to ASTM D1922. FIG. 1 plots the Elmendorf tear values for the machine direction (“MD”) and the cross direction (“CD”), as well as the MD / CD ratio of the Elmendorf tear va...

example 3

[0119]

TABLE 67.1:1 Draw RatioLayerCompositionThickness (μ)(μ)A (First Layer)100% EPE406.1B (Inner Layer)70% EPE-HD;253.830% Z-N ULDPEC (Second100% Z-N ULDPE355.3Layer)C100% Z-N ULDPE355.3B70% EPE-HD;253.830% Z-N ULDPEA100% EPE406.1Total Thickness20030.5

The Example 3 film stretches easily at 225° F., and is substantially flat. The film also shows excellent optical properties. Measurements are taken to evaluate the Example 3 film's orientation performance The Example 3 film had an initial roll width of 1600 mm, a roll width after 7:1 orientation in the machine direction of 1430 mm, and a final roll width after edge trimming of 1260 mm. These values represent a width retraction after orientation in the machine direction of 10.63%, and a total width reduction of 21.25% after edge trimming.

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PUM

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Abstract

The present invention provides uniaxially oriented films and packages formed from such films. In one aspect, a uniaxially oriented film comprises (a) a first layer including (i) a first composition including an ethylene-based polymer prepared in the presence of a single-site catalyst, wherein the first composition has a density of 0.935 g / cm3 to 0.965 g / cm3, a melt index (I2) of 0.5 to 6 g / 10 minutes, and a MWD of 6.0 or less, and (ii) a Ziegler-Natta catalyzed ultra low density polyethylene having a density of 0.880 g / cm3 to 0.912 g / cm3, a melt index (I2) of 0.5 to 6 g / 10 minutes, and a MWD of 6.0 or less, (b) a second layer including at least one polyolefin, and (c) at least one inner layer between the first layer and the second layer including a high density polyethylene. The film is oriented in the machine direction at a draw ratio of between 4:1 and 10:1, and can exhibit a machine direction 2% secant modulus of 85,000 psi or more when measured as per ASTM D882.

Description

FIELD[0001]The present invention relates to uniaxially oriented, multi-layered films and in particular, to multi-layered films oriented in the machine direction. Such films can be particularly useful in articles such as flexible packaging.INTRODUCTION[0002]Polyethylene films are widely used in flexible packaging, such as heavy duty shipping sacks, stand-up pouches, detergent pouches, sachets, etc. Depending on the application, a variety of properties may be needed in terms of integrity and / or attractiveness. Such properties can include: (1) excellent optical properties, such as high gloss, high clarity and low haze; (2) sufficient abuse resistance, such as high tensile strength, high puncture, stiffness and impact resistance; and / or (3) good sealing properties, such as low seal initiation temperature, broad sealing window, high seal strength and high hot tack.[0003]Conventional blown or cast polyethylene films were widely used in flexible packaging, either as stand-alone packaging o...

Claims

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Application Information

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Patent Type & AuthorityPatents(United States)
IPC IPC(8): B32B27/32B32B27/08C08L23/06
CPCB32B27/327B32B27/08B32B27/32C08L23/06B32B2250/242B32B2270/00B32B2307/30B32B2307/516B32B2307/72B32B2323/043B32B2323/046B32B2439/70B32B2553/00C08L2207/064C08L2314/02C08L2314/06
InventorBARRENECHE, FELIPE MARTINEZ
OwnerDOW GLOBAL TECH LLC